1. Field of the Invention
The present invention relates to an optical fiber cable incorporating a multi-core fiber with a plurality of cores each extending along a predetermined axis.
2. Related Background Art
For realizing large-capacity optical transmission, there are known multi-core fibers configured so that a cladding region integrally surrounds a plurality of cores.
For example, the multi-core fiber described in Document 1 (Masanori KOSHIBA, et al., “Heterogeneous multi-core fibers: proposal and design principle,” IEICE Electronics Express, Vol. 6, No. 2, pp. 98-103, 2009) is able to realize a low crosstalk level because a power transfer rate between adjacent cores becomes sufficiently low by changing a difference between relative refractive-index differences Δ of adjacent cores to the cladding (the relative refractive-index difference of each core will be referred to hereinafter as core Δ) by a very small amount (e.g., 0.005%). Document 1 describes that this technique can realize the multi-core fiber with three kinds of cores different in core Δ and with the cladding diameter of 125 μm. However, nothing is considered about bending of the fiber.